Revenge and the brain: 'I did it for love' isn't so crazy

Research shows that our brain — with the help of a little love and empathy — may drive us to seek revenge.

Jordan Heuvelmans 3 minute read March 5, 2020

Research shows the brain's role in revenge. Stock/ Getty

Popular teen movies like Carrie and Mean Girls have all centred around the theme of revenge. And while watching someone on screen get ‘what they deserved’ can be satisfying, science is now shedding light on the brain processes that lead to revenge in times of conflict. It’s actually pretty fetch.

A new study in the journal eLife provides new insights into how the neural processes in our brains drive a desire for revenge in conflicts between groups. The findings suggest that the ‘love drug’ oxytocin increases during times of conflict between groups and influences the part of our brain associated with decision-making activity (known as the medial prefrontal cortex). This, in turn, leads to a greater feeling of love and empathy for those in the group and a need to seek revenge when attacked by outsiders. The researchers say the findings may help explain how a process called “conflict contagion” occurs — which describes what happens when a conflict between a few people spreads across entire groups.

“The desire to seek revenge for an attack during conflict is universal among humans, but the neurobiological processes that drive it are still unclear,” lead author Xiaochun Han, Doctor of Psychology and Neuroscience at the School of Psychological and Cognitive Sciences, PKU-IDG/McGovern Institute for Brain Research, said in a press release to EurkAlert.

“Building upon previous studies, we suggest there may be a neurobiological mechanism that links pain within a group, known as the ‘ingroup’, caused by an outside group, or ‘outgroup’, with the tendency to seek revenge upon the outgroup,” said Xiaochun, who is with the Peking University in China.

To learn more, researchers developed an experiment that simulated real life revenge during conflict between groups. Since oxytocin is known for regulating conflict and plays a role in empathy, they wanted to look at how oxytocin and neural responses to suffering from an outside force would impact a group’s desire for revenge.

Participants watched an ingroup and an outgroup member get an electric shock that was caused either by a computer or mutually by other members. The team combined a brain imaging technique known as functional magnetic resonance imaging to measure the levels of oxytocin in the participants. They found that those who gave an electric shock to others had higher levels of oxytocin, which in turn predicted the medial prefrontal activity. This, in turn, predicted the desire to seek revenge on the other group, regardless of which individuals were involved in the conflict.

“The results highlight an important neurobiological process underpinning the desire for revenge, which may be implicated in conflict contagion during conflict among groups.” said senior author Shihui Han, Professor at the Department of Psychology and Principle Investigator at PKU-IDG/McGovern Institute for Brain Research, Peking University in a press release for EurkAlert.

Shihui said that there are various reasons group members seek revenge such as feeling threatened, feeling badly about the harm done towards another member, or pressure to avenge other group members. The researchers say that more studies are needed to determine the motivations and emotions associated with revenge to understand what drives humans to seek it.